A movable wall system comprised of a plurality of continuously hinged panels is traditionally extended or retracted (stacked) by either manual means or with the assistance of an overhead electrical chain drive system. Electric systems may be desirable for a multitude of reasons, such as the weight of the panels (and the force required to move the wall) being prohibitive for a typical individual to move manually, or simply for convenience. Aptly powered electrical systems are successful in moving the wall, but, as described below, are often inefficient when "flattening" the wall once it is nearly fully extended and when "breaking" the wall to begin retracting the wall from its fully extended position. These inefficiencies are translated into increased costs in manufacturing and in maintaining the electrically driven systems. Alternatives need to be provided which are both efficient and cost effective.
When extending a movable wall, it is important that all of the wall panels be completely coplanar or "flattened" for a variety of reasons. Aesthetically, the wall will be more pleasing if it is entirely flat thereby appearing more like permanent walls. If the wall is dividing areas in which limited sound transmission between the rooms is of concern, there must be no gaps between the panels of the movable wall, nor should there be gaps at either end of the movable wall. Any gaps significantly reduce the acoustic quality of the wall. Also, it is very important that the wall be fully extended, rigid, and locked into position, so that the wall does not begin to retract if a force is inadvertently applied to move the wall toward the stacked position.
Some electrically driven systems incorporate large motors, that provide much more horsepower than actually required to move the wall, to solve the flatness problem. These systems use so much force to extend the wall that the panels "snap" into place from inertial force. This is an expensive solution, not only in terms of manufacturing costs, but also in the maintenance of the systems since the electric motor will experience undue loads while attempting to flatten the wall and, hence, its life cycle may be shortened.
To assist an electric system in solving the flatness problem, some systems connect adjacent panels with cables and/or springs to straighten the wall when near the fully extended position. These systems are costly to manufacture, are difficult to service as they require constant adjustment to function properly, and have a tendency to destroy the trim on the panel.
When retracting (stacking) the continuously hinged movable wall, several methods are used to begin the retraction process. The retraction process will begin very simply if a deflection is made in the joint between adjacent panels that are closest to the stack jamb. This is called "breaking" the wall. In some systems, this deflection must be made manually, i.e. by a person pushing the abutting edges of the two adjacent panels to cause the panels to pivot. Another method is to use a "retraction bar." This bar is connected via a pivot point to the top of the panel closest to the stack jamb and is fixed to the ceiling. As the drive motor urges the panels toward the retracted position, the retraction bar translates the backward force to a sideward force, causing the trailing panel to break. This type of breaking assembly still requires a large motor to create a break in the wall and imposes undue stress on the motor, thus reducing motor life span. In addition, a retraction bar is inappropriate for a movable wall system with stringent sound transmission requirements as the bar protrudes through the upper trim of the first panel. Moreover, a retraction bar is aesthetically undesirable as it is visible. Finally, the retraction bar is a control system independent from the electric drive, so the functions of each are not coordinated.